Solvent fractionation of waxcontaining mixtures



Dec. 11, 1951 E. w. CLARKE v 2,578,510

SOLVENT FRACTIONATION OF WAX-CONTAINING MIXTURES Filed Sept. 16, 1947 sZHDDITIVZ HTTEST INVENTOR. G (B Ea f afi Clarke W y/1A4, 85 K4! Patented Dec. 11, 1951 SOLVENT FRACTIONATION OF WAX- CONTAINING MIXTURES Edgar W. Clarke, Laurel Springs, N. J., assigncr to The Atlantic Refining Company, Philadelphia, Pa., a corporation of Pennsylvania Application September 16, 1947, Serial No. 774,230

8 Claims. i

The present invention relates to the treatment of oily waxes, and more particularly to the separation of wax-containing mixtures into fractions of higher and lower melting point.

The present invention is especially applicable to the de-oiling of hydrocarbon waxes containing not more than about 70% of oil, and to the separation of wax mixtures of low oil content into fractions of difierent melting point. The process of the present invention may be applied in the refining, purification, or separation of wax stocks such as petroleum slack wax, crude microcrystalline wax, paraffin waxes, petrolatum wax, montan wax, ceresin, ozokerite, waxes from the destructive Or non-destructive hydrogenation of mineral oil, synthetic hydrocarbon oil, shale oil, coal, and waxes produced synthetically by the catalytic reaction of hydrocarbons, or waxes derived from the modified Fischer-Tropsch reaction of carbon monoxide and hydrogen. The process of this invention is especially applicable in the separation of wax mixtures containing color bodies and oil into a higher melting wax fraction of light color and low oil content, and a lower melting wax fraction of darker color and containing most of the oil originally present in the wax mixture.

In accordance with this invention, a Waxcontaining mixture is separated into fractions of higher and lower melting point by countercurrently contacting the wax-containing mixture in an extraction zone with an extraction solvent and a solvent additive or additives at a temperature such that two liquid phases are formed, one comprising the higher melting wax fraction with minor amounts of solvent and additive, and the other comprising the lower melting wax fraction with major amounts of solvent and additive, sep; arating the liquid phases from one another. and removing the solvent and additive from each. The extraction solvent and additives employed may have a density greater than that of the wax.

However, when the additive or additives are partially immiscible with the extraction solvent and are less dense than such solvent or the wax, the additive or additives will flow countercurrent to the extraction solvent and will appear with that liquid phase comprising the higher melting wax fraction. The success of the process depends upon the control of the temperature throughout the extraction zone and upon the regulation of the proportions of solvent and additive used, and the points of introduction of the wax-containing mixture, the solvent, and the additive into the extraction zone.

The extraction solvent may be defined as an I agent, which, when intimately mixed with a waxcontaining mixture, forms two liquid phases or layers, one comprising a rafiinate phase containing mostly wax of higher melting point than the untreated wax and a portion of the solvent, and

' the other comprising an extract phase containing mostly solvent, and wax of lower melting point than the untreated wax, as well as a major portion of the color bodies and oil originally present in the untreated wax.

The solvent additive may be defined as an agent used in conjunction with the extraction solvent for the purpose of modifying the characteristics of the extraction solvent. The additive may lower the temperature at which solid wax precipitates out of the extraction solvent, or it may raise the miscibility temperature of the extraction solvent with the wax. However, the additive chosen for a particular extraction solvent must not excessively lower the selectivity of the extraction solvent at the temperature of extraction.

The extraction solvent may be employed in amounts ranging from. 1 to 5 voltunes of solvent per volume of untreated wax stock, while the additive or additives may be used in amounts ranging from 0.05 to 1 volumes per volume of untreated wax.

The extraction solvents which may be employed in accordance with the present invention include nitrobenzene, phenol (preferably anhydrous or containing only a small amount of water), pyridine, acetone, and nitrobenzene containing a small amount of phenol, or of BB- .dichlordiethyl ether, or of furfural.

The solvent additive or additives, which are usually employed in amounts constituting not more than 50% by volume of the extraction solvent, include parafiinic hydrocarbons of from 3 to 10 carbon atoms, paraffinic naphtha or kerosine, BB-dichlordiethyl ether, furfural, phenol, phenol containing 20% to of water, cresol, ethylene, glycol mono-methyl ether. nitroethanc, nitropropane, diethylene glycol, aniline, and water.

The process of the present invention may be carried out in a multi stage batch countercurrent extraction system or in a continuous countercurrent extraction system, preferably a tower provided with perforated baiiles or containing a packing material such as ceramic shapes, tiles, metal wool, or fragments of ceramic material, glass, pumice, carborundum, or concrete. For most effective operation, a temperature gradient is maintained in the system by means of heating 3 or cooling coils or jackets, the temperature increasing in the direction of flow of the raffinate or higher melting wax fraction.

The present invention may be further understood with reference to the accompanying drawin which illustrates diagrammatically a continuous extraction system suitable for carrying out the process.

Referring to the drawing, a dark colored microcrystalline wax having a melting point of 171.5" F. and an oil content of 5% is continuously introduced, in liquid condition, into the extraction tower I through valve controlled pipe 2 at a rate of 100 volumes per hour. An extraction solvent comprising nitrobenzene containing 5% of anhydrous phenol is continuously introduced from vessel 3 by means of valve-controlled pipe 4 and manifold 5 into the upper section of the tower below the rafiinate outlet at a rate of 240 volumes per hour. The first additive comprising substantially anhydrous phenol is continuously introduced from vessel 6 through valve-controlled pipe 1 into the extraction tower I below the wax inlet at a rate of 30 volumes per hour. The second additive comprising phenol containing 30% of water is continuously introduced by valvecontrolled pipe 8 into the extraction tower I between the point of introduction of the first additive and the outlet of the extract phase, at a rate of 30 volumes per hour. The second additive is made up by mixing phenol delivered from vessel 6 through valve-controlled pipe I and water from vessel 9. An intimate countercurrent contacting of the wax stock, the extraction solvent, and the additives is effected in tower I, a temperature gradient being maintained in the tower by means of coils l I through which a heating or cooling medium is circulated as required. The temperature adjacent the top of the tower is held at 172 F. and adjacent the bottom of the tower at 166 F., the contents being entirely in the liquid phase. The wax stock, being subjected to the action of the solvent and additives, is caused to separate by solvent action into two fractions, the higher melting fraction wax passing upwardly through the tower together with a minor amount of dissolved extraction solvent and additive, and being withdrawn therefrom above the level of the dotted line I2 representing the higher melting wax phase relatively free of entrained, immiscible solvent and additive. The rafiinate phase comprising the higher melting wax and dissolved solvent and additive is passed from the top of tower I through valvecontrolled pipe I3 into a vacuum evaporator or still I4 wherein the solvent and additive is removed from the higher melting wax by vaporization, the solvent and additive vapors passing through pipe I5 into fractionating tower I6 provided with a reboiler or heating coil I'I, while the higher melting wax is drawn from the bottom of evaporator I4 and delivered by valvecontrolled pipe I8 into storage vessel I9. Such wax fraction was a very light yellow color, and had a melting point of 193 F. and an oil content of 0.5% by weight, the yield being 49.3% of the wax stock originally charged. The oil content was determined by the A. S. T. M. method D721-44 (1946).

The extract phase comprising the lower melting wax fraction, color bodies, oil, and the major portion of the extraction solvent and additives is withdrawn from the lower section of tower l beneath the level of the dotted line 20 representin the extract phase relatively free of entrained,

higher melting wax. The extract phase is delivered by valve-controlled pipe 2| into a vacuum evaporator or still 22 wherein the solvent and additives are vaporized from the lower melting wax, the latter being drawn from the bottom of the evaporator and passed by valve-controlled pipe 23 to storage vessel 24. The lower melting wax, amounting to 50.7% of the wax stock charged, was brown in color and had a melting point of 150.6 F. and an oil content of 9.4% by weight.

The solvent and additive vapors are passed from the top of evaporator 22 through pipe 25 into fractionating tower I5, wherein such vapors together with those introduced through pipe I5, are fractionated, the extraction solvent, i. e., nitrobenzene, being drawn from the bottom of the tower as a liquid and returned by means of pipe 26 to the solvent storage vessel 3 for reuse. The nitrobenzene may contain small amounts of phenol, and additional phenol may be incorporated in the nitrobenzene to bring the phenol content up to 5% in the solvent contained in vessel 3. This may be accomplished by introducing phenol from vessel 6 by means of valve-controlled pipe 21. The additives, i. e., phenol and water, separated from the nitrobenzene by fractionation in tower I3 are taken overhead as vapors by pipe 28 and introduced into a second fractionating tower 29 provided with heating coil 33. A portion of the vapor stream may be diverted through valve-controlled pipe 3I, condensed in condenser 32, and the condensate returned as reflux to the top of tower It by pipe 33.

In tower 29, the major portion of the water is removed from the phenol by fractionation, the water being taken overhead as vapor through pipe 34, condensed in condenser 35, and returned by pipe 33 to vessel 9. This water may contain small amounts of phenol (up to 10%), the presence of which is not deleterious when the water is subsequently used in the extraction tower I. Phenol containing very little water is drawn from the bottom of fractionating tower 29 and returned by pipe 37 to vessel 6. If desired, a portion of the phenol may be passed from pipe 37 through valve-controlled pipe 2'! into vessel 3 to adjust the percentage of phenol in the nitrobenzene contained in vessel 3.

Depending upon the temperature of operation, the first additive may be introduced somewhat above the point of introduction of the liquified wax stock, for example, by means of value-controlled pipe 38 rather than through valve-controlled pipe I, in which case the second additive may be admitted through either or both of valvecontrolled pipes I and 8 below the point of introduction 0f the wax stock. In general, the raffinate wax phase withdrawn from the extraction tower will contain from 5% to 25 of solvent and additive, while the extract wax phase will contain from 55% to of solvent and additive.

While, in the extraction system above described, a specific combination of an extraction solvent and additives were used, it is obvious that various other combinations may be employed, depending upon the nature of the wax stock to be treated, the extraction temperatures, and the extent to which the wax stock is to be separated into components. In the event that the extraction is to be carried out in a multi-stage batch counter-current system, using the solvent and additives specifically set forth above, the wax stock would be introduced into the 1st stage extractor. the extraction solvent (nitrobenzene containing 5% of anhydrous phenol) would be introduced into the 3rd stage extractor, and the first additive, i. e., anhydrous phenol would be introduced into the second stage extractor. The second additive, e. g., phenol containing 30% of water, would be introduced into the 1st stage extractor, from which the extract phase is with drawn, while the rafiinate phase would be removed from the 3rd stage extractor. The tern- V perature would be 166 F. in the 1st stage, 169 F.

in the second stage, and 172 F. in the third stage, using the microcrystalline wax stock, solvent, and additives described hereinabove. It is to be understood, of course, that the quantities and composition of the solvent and of the additives may be varied within certain limits, and that some modification of the extraction system will be necessary depending upon the properties of the solvents and additives used. This is especially true when the additive or additives are hydrocarbons such as C: to C paraffin hydrocarbons, parafiinic naphtha, or parafiinic kerosine, in which case these additives would leave the ex: traction system with the raffinate phase, i. e., the higher melting wax fraction, and would be separated and recovered therefrom by distillation.

Exemplary of the various solvent and additive materials which may be used in accordance with this invention are the following, the quantlties being volumes per unit volume of wax stock.

Extraction Solvent 1st Additive 2nd Additive nitrobenzene, 251.4 anhyd. phenol, 0.31%; phenol-120% water,

vols. 0.05 vols. 031110.05 "01s.

Do ..(lo anhyd. phenol, 03

0.05 vols. Do ethylene glycol monoethylene glycol monomethyl ether, 0.1111 methyl ether, 0.1111 0.05 vols. 0.05 vols. nltrobenzene+2%... do Do.

6t ylene glycol monomethyl ether, 21110.4 vols. nitrobenzene+5% anhyd. phenol, 03 phenol+30% water0.3

phenol, 21110.4 vols. 0.05 vols. 10.05 vols. nltrobenzene+10% B B- dichlordiethyl BB-dichlordiethyl BB'-d i c h l o r d i ether, 0.l1110.05 vols. ether, 011110.05 vols. etlliyl ether, 21110.4 vo s. nitrobenzene+10% furfural, 021110.05 vols. furfural, 021110.05 vols.

furfural, 21110.4

vols. pyridine, 3310.5 vols.

pyridlnc,.3i0.5 vols.

acetone, 4&05 vols v s. nitrobcnzene+10% iurfural, 21110.2

nitrobenzene+10% phenol, 2i0.2 vols.

anhyd. phenol, 3:1:

0.4 vols.

B'B-dichlordiethyl ether, 0.4i0.1 vols. nitroethane, 0.411101 ethylene glycol monomethyl ether, 0.41 0.1 vols. diethylene glycol 0.41|10.l vols.

aniline, 0.51i10.l.vols

cresol, 0.411101 vols...

iurfural, OAiOJ vols.

ethylene glycolmonomethyl ether, 02:1: 0.05 vols.

BB'-dichlordiethy1 ether,.0.21l10.05 vols.

Iurfural, 0.411101 vols.

- phenol+20% water,

0.2i0.05 vols. water, 031110.05 vols parafhnic vols.

Cu to C10 pared-ins,

0.511101 vols.

kerosine, 0.611101 vols.

nitropropane, 0.4i01 vols.

ethylene glycol monomethyl ether, 0.411: 0.1 vols. diethylene glycol,

0.41 101 vols. aniline, 0.51 101 vols. cresol, 0.411101 vols. furfural, 0.411101 vols.

acetonc+5% water,

The present invention is further illustrated by the following examples, which, however, are not to be construed as limiting the scope thereof.

(1) A slack. wax having a melting point of 112.6 F. and an oil content of 41.3% by weight was extracted in a systemsimilar to. that shown in the accompanying drawing, the extraction solvent comprising 2 volumes of nitrobenzene containing 5% of anhydrous phenol. the first additive comprising 0.3 volumes of anhydrous phenol, and the second additive comprising 0.3 volumes of phenol containing 30% of water. The temperature gradient in the extraction tower ranged from F. at the bottom thereof to F. at the top thereof. After countercurrent contacting and removal of the rafiinate phase from the top of the tower, and the extract phase from the bottom of the tower, the solvent and additives were recovered from the wax fractions by vacuum evaporation and fractionation. The

rafiinate wax obtained in a 50% yield, was white and had a melting point of 132 F. and an oil content of 0.6% by weight. The extract wax also obtained in a 50% yield was dark brown, and had a melting point of 90 F. and an oil content of 82% by weight. The rafiinate wax was further characterized by its firmness, good tac'lriness and plasticity, long fiber length, and moderate flexibility.

(2) The same slack wax used in Example 1 was extracted with a different combination of solvent and additives, namely, an extraction solvent comprising 2 volumes of nitrobenzene containing 10% of anhydrous phenol, the first additive comprising 0.2 volumes of phenol containing 20% of water, and the second additive comprising 0.5 volumes of paraninic kerosine. The temperature gradient in this extraction ranged from 95 F. to to 135 F. A raffinate Wax obtained in a yield of 54% was white, and had a melting point of 132.6" E. and zero oil content. The extract wax,

amounting to 46%, was dark brown and had a melting point of 875 F. and an oil content of 90% by weight.

(3) A refined paraffin wax having a melting point of 132 F. and an oil content of 1.2% by weight was separated into fractions using an ex traction solvent, comprising 2 volumes of nitrobenzene containing 5% of phenol, the first additive comprising 0.3 volumes of anhydrous phenol. and the second additive comprising 0.3 volumes of phenol containing 10% of water. The temperature gradient ranged from 125 F. to F. A raffinate wax was obtained in a yield of 50%, and had a melting point of 141-F. and an oil content of 0.5% by weight. The extract wax, amounting to 50%, had a melting point of 122 F. and an oil content of 1.9% by weight.

Where the extraction operation is conducted in a tower, it has been found that a tower having a height of about 40 feet and a diameter of 6 feet is satisfactory. The tower is provided with suitable packing to within about 4 feet of the top and bottom thereof, such spaces functioning as quiescent zones in which entrained materials are permitted to separate from the rafiinate and. extract phases, respectively. In such a tower, the wax stock is charged at a point about 13 feet from the bottom thereof, or approximately the distance from the bottom of the tower. The extraction solvent is charged just above the upper level of the packing, for example, 3 to efeet from the top of the tower. The first additive may be introduced adjacent the point of introduction of the wax stock, for example, 2 feet above or below the wax inlet. The second additive is introduced approximately 2 feet below the point of introduction of the first additive. These values may be altered somewhat, depending upon the tower design, the solvent and additives used, and the temperatures maintained at various levels in the tower. The

raflinate phase is withdrawn from the top of the tower, and the extract phase from the bottom thereof, the extraction solvent being more dense than the wax stock.

I claim:

1. The method of separating a wax-containing mixture into fractions of higher and lower melting point, which comprises countercurrently contacting said wax-containing mixture in an extraction zone with an extraction solvent and solvent additives at a temperature such that two immiscible liquid phases are formed, one comprising the higher melting wax fraction containing solvent and additives, and the other comprising solvent and additives and the lower melting wax fraction, separating the phases from one another, and removing the solvent and additives from each, the solvent comprising 1.6 to 2.4 volumes of nitrobenzene per volume of wax-containing mixture, the first additive comprising 0.25 to 0.35 volumes of substantially anhydrous phenol per volume of wax-containing mixture, and the second additive comprising 0.25 to 0.35 volumes of aqueous phenol containing 20% to 30% of water per volume of wax-containing mixture.

2. The method of separating a wax-containing mixture into fractions of higher and lower melting point, which comprises countercurrently contacting said wax-containing mixture in an extraction zone with an extraction solvent and a solvent additive at a temperature such that two immiscible liquid phases are formed, one comprising the higher melting wax fraction containing solvent and additive, and the other comprising solvent and additive and the lower melting wax fraction, separating the phases from one another, and removing the solvent and additive from each, the solvent being introduced into the extraction zone near the point of withdrawal of the higher melting wax fraction and the additive being introduced adjacent the point of introduction of the wax-containing mixture, the solvent comprising 1.6 to 2.4 volumes of nitrobenzene per Volume of wax-containing mixture, and the additive comprising 0.25 to 0.35 volumes of phenol per volume of wax-containing mixture.

3. Themethod of separating a wax-containing mixture into fractions of higher and lower melting point, which comprises countercurrently contacting said wax-containing mixture in an extraction zone with an extraction solvent and solvent additives at a temperature such that two immiscible liquid phases are formed, one comprising the higher melting wax fraction ccntaini'ng solvent and additives, and the other comprising solvent and additives and the lower melting wax fraction, separating the phases from one another, and removing the solvent and additives from each, the solvent being introduced into the extraction zone near the point of withdrawal of the higher melting wax fraction, the first additive being introduced adjacent the point of introducticn of the wax-containing mixture, and the second additive being introduced between the point of introduction of the first additive and the point of withdrawal of the lower melting wax fraction, the solvent comprising 1.5 to 2.4 volumes of nitrobenzene per volume of wax-containing mixture, the first additive comprising 0.25 to 0.35 volumes of substantially anhydrous phenol per volume of wax containing mixture, and the second additive comprising 0.25 to 0.35 volumes of aqueous phenol containing 8 20% to 30% of water per volume of wax-containing mixture.

4. The method of separating a wax-containing mixture into fractions of higher and lower melting point, which comprises countercurrently contacting said wax-containing mixture in an extraction zone with an extraction solvent and a solvent additive at a temperature such that two immiscible liquid phases are'formed, one comprising the higher melting wax fraction with minor amounts of solvent and additive, and the other comprising the lower melting wax fraction with major amounts of solvent and additive, separating the phases from one another, and removing the solvent and additive from each, the

solvent being introduced into the extraction zone near the point of withdrawal of the higher melting wax fraction and the additive being introduced between the point of withdrawal or" the lower melting wax fraction and the point of introduction of the wax-containing mixture, the solvent comprising 1.6 to 2.4 volumes of nitrobenzene per volume of wax-containing mixture. and the additive comprising 0.25 to 0.35 volumes of phenol per volume of wax-containing mixture.

5. The method of separating a wax-containing mixture into fractions of higher and lower melting point, which comprises countercurrently contacting said wax-containing mixture in an extraction zone with an extraction solvent'and solvent additives at a temperature such that two immiscible liquid phases are formed, one comprising the higher melting wax fraction with minor amounts of solvent and additives, and the other comprising the lower melting wax fraction with major amounts of solvent and additives, separating the phases from one another, and removing the solvent and, additives.

from each, the solvent being introduced into the extraction zone near the point of withdrawal of the higher melting wax fraction, the first additive being introduced between the point of introduction of the wax-containing mixture and the point of withdrawal of the lower melting wax fraction," and the second additive being introduced between the point of introduction of the first additive and the point of withdrawalof the lower melting wax fraction, the solvent comprising 1.6 to 2.4 volumes of nitrobenzene per volume of wax-containing mixture, the first additive comprising 0.25 to 0.35 volumes of substantially anhydrous phenol per volume of waxcontaining mixture, and the second additive comprising 0.25 to 0.35 volumes of aqueous phenol containing 20% to 30% of water per volume of wax-containing mixture.

6. In a method of separating a wax-containing mixture into fractions of higher and lower melting point, wherein the wax-containing mixture is contacted in an extraction zone with an extraction solvent and solvent additives at a temperature above the melting point but below the temperature of complete miscibility of the mixture, the steps which comprise introducing 1 volume of liquified wax-containing mixture into the extraction zone at a point intermediate the points of withdrawal of the higher and lower meiting waxes including the solvent and additive, introducing 1.6 to 2.4 volumes of extraction sol vent comprising nitrobenzene at a point adjacent the point of Withdrawal of the higher melting wax fraction including. solvent and additive, but intermediate said point of withdrawal and the the point of introduction of the liquified waxcontaining mixture, and introducing 0.25 to 0.35

volumes of an additive comprising substantially anhydrous phenol intermediate the point of introduction of the liquified wax-containing mixture and the point of withdrawal of the lower melting wax fraction including solvent and additive, introducing 0.25 to 0.35 volumes of an additive comprising aqueous phenol containing 20% to 30% water at a point intermediate the point of introduction of the anhydrous phenol and the point of withdrawal of the lower melting wax fraction including solvent and additive, effecting countercurrent contact between the liquified wax-containing mixture and the solvent and additives at a temperature such that two immiscible liquid phases are, formed, one phase comprising the higher melting wax fraction containing minor amounts of solvent and additives, and the other liquid phase comprising the lower melting wax fraction and major amounts of solvent and additives, the temperature in the extraction zone increasing in the direction of flow of the higher melting wax fraction, separately withdrawing the respective liquid phases from the extraction zone, and removing the solvent and additives from each.

'7. The method of separating a wax-containing mixture into fractions of higher and lower melting point, which comprises countercurrently contacting said wax-containing mixture in an extraction zone with an extraction solvent and solvent additives at a temperature such that two immiscible liquid phases are formed, one comprising the higher melting wax fraction containing solvent and additives, and the other comprising solvent and additives and the lower melting wax fraction, separating the phases from one another, and removing the solvent and additives from each, the solvent being introduced into the extraction zone near the point of withdrawal oi the higher melting wax fraction, the first additive being introduced adjacent the point of introduction of the wax-containing mixture, and the second additive being introduced between the point of introduction of the first additive and the point of withdrawal of the lower melting wax fraction, the solvent comprising 1.6 to 2.4 volumes of nitrobenzene containing of phenol per volume of wax-containing mixture, the first additive comprising 0.25 to 0.35 volumes of substantially anhydrous phenol per volume of wax-containing mixture, and the second additive comprising 0.25 to 0.35 volumes of aqueous phenol containing 20% to 30% of water per volume of wax-containing mixture.

8. The method of separating a wax-containing mixture into fractions of higher and lower melting point, which comprises countercurrently contacting said wax-containing mixture in an extraction zone with an extraction solvent and solvent additives at a temperature such that two immiscible liquid phases are formed, one comprising the higher melting wax fraction containing solvent and additives, and the other comprising solvent and additives and the lower melting wax fraction, separating the phases from one another, and removing the solvent and additives from each, the solvent being introduced into the extraction zone near the point of withdrawal of the higher melting wax fraction, the first additive being introduced adjacent the point of introduction of the wax-containing mixture, and the second additive being introduced between the point of introduction of the first additive and the point of withdrawal of the lower melting wax fraction, the solvent comprising 1.6 to 2.4 volumes of nitrobenzene per volume of waxcontaining mixture, the first additive comprising 0.25 to 0.35 volumes of substantially anhydrous phenol per volume of wax-containing mixture, and the second additive comprising 0.25 to 0.35 volumes of substantially anhydrous phenol per volume of wax-containing mixture.

EDGAR W. CLARKE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,017,432 Bahlke Oct. 15, 1935 2,063,369 Diggs et al. Dec. 8, 1936 2,137,549 Subkow Nov. 22, 1938 2,138,833 Brown et al Dec. 6, 1938 2,141,361 Pilat et al. Dec. 27, 1938 2,160,930 Whiteley et al. June 6, 1939 2,216,933 Atkins Oct. 8, 1940 2,261,799 Franklin Nov. 4, 1941 2,302,434 Dons et al. Nov. 1'7, 1942 

1. THE METHOD OF SEPARATING A WAX-CONTAINING MIXTURE INTO FRACTIONS OF HIGER AND LOWER MELTING POINT, WHICH COMPRISES COUNTERCURRENTLY CONTACTING SAID WAX-CONTAINING MIXTURE IN AN EXTRACTION ZONE WITH AN EXTRACTION SOLVENT AND SOLVENT ADDITIVES AT A TEMPERATURE SUCH THAT TWO IMMISCIBLE LIQUID PHASES ARE FORMES, ONE COMPRISING THE HIGHER MELTING WAX FRACTION CONTAINING SOLVENT AND ADDITIVES, AND THE OTHER COMPRISING SOLVENT AND ADDITIVES AND THE LOWER MELTING WAX FRACTION, SEPARATING THE PHASES FROM ONE ANOTHER, AND REMOVING THE SOLVENT AND ADDITIVES FROM EACH, THE SOLVENT COMPRISING 1.6 TO 2.4 VOLUMES OF NITROBENZENE PER VOLUME OF WAX-CONTAINING MIXTURE, THE FIRST ADDITIVE COMPRISING 0.25 TO 0.35 VOLUMES OF SUBSTANTIALLY ANHYDROUS PHENOL PER VOLUME OF WAX-CONTAINING MIXTURE, AND THE SECOND ADDITIVE COMPRISING 0.25% TO 0.35 VOLUMES OF AQUEOUS PHENOL CONTAINING 20% TO 30% OF WATER PER VOLUMER OF WAX-CONTAINING MIXTURE. 